jQuery.extend({
    createUploadIframe: function(id, uri) {
		// create frame
        var frameId = 'jUploadFrame' + id;
        var iframeHtml = '<iframe id="' + frameId + '" name="' + frameId + '" style="position:absolute; top:-9999px; left:-9999px"';
		if(window.ActiveXObject) {
            if (typeof uri == 'boolean') {
				iframeHtml += ' src="' + 'javascript:false' + '"';
            } else if(typeof uri == 'string') {
				iframeHtml += ' src="' + uri + '"';
            }
		}
		iframeHtml += ' />';
		jQuery(iframeHtml).appendTo(document.body);

        return jQuery('#' + frameId).get(0);
    },
    createUploadForm: function(id, fileElementId, data) {
		// create form
		var formId = 'jUploadForm' + id;
		var fileId = 'jUploadFile' + id;
		var form = jQuery('<form  action="" method="POST" name="' + formId + '" id="' + formId + '" enctype="multipart/form-data"></form>');
		if (data) {
			for (var i in data) {
				jQuery('<input type="hidden" name="' + i + '" value="' + data[i] + '" />').appendTo(form);
			}
		}
		/*var oldElement = jQuery('#' + fileElementId);
		var newElement = jQuery(oldElement).clone();
		jQuery(oldElement).attr('id', fileId);
		jQuery(oldElement).before(newElement);
		jQuery(oldElement).appendTo(form);*/
		
		/*
		 * 支持多文件上传（单文件上传也支持）
		 * 单文件：
		 * fileElementId: 'field_name1'
		 * 多文件：
		 * fileElementId: ["field_name1", "field_name2"]
		 */
		if (typeof(fileElementId) == 'string') {
			fileElementId = [fileElementId];
		}
		for(var i in fileElementId) {
			// 按name取值
			var oldElement = jQuery("input[name="+fileElementId[i]+"]");
			oldElement.each(function() {
				var newElement = jQuery($(this)).clone();
				jQuery(oldElement).attr('id', fileId);
				jQuery(oldElement).before(newElement);
				jQuery(oldElement).appendTo(form);
			});
		}

		// set attributes
		jQuery(form).css('position', 'absolute');
		jQuery(form).css('top', '-1200px');
		jQuery(form).css('left', '-1200px');
		jQuery(form).appendTo('body');
		return form;
    },

    ajaxFileUpload: function(s) {
        // introduce global settings, allowing the client to modify them for all requests, not only timeout
        s = jQuery.extend({}, jQuery.ajaxSettings, s);
        var id = new Date().getTime();
		var form = jQuery.createUploadForm(id, s.fileElementId, (typeof(s.data) == 'undefined' ? false : s.data));
		var io = jQuery.createUploadIframe(id, s.secureuri);
		var frameId = 'jUploadFrame' + id;
		var formId = 'jUploadForm' + id;
        // Watch for a new set of requests
        if (s.global && ! jQuery.active++) {
			jQuery.event.trigger("ajaxStart");
		}
        var requestDone = false;
        // Create the request object
        var xml = {};
        if (s.global)
            jQuery.event.trigger("ajaxSend", [xml, s]);
        // Wait for a response to come back
        var uploadCallback = function(isTimeout) {
			var io = document.getElementById(frameId);
            try {
				if (io.contentWindow) {
					xml.responseText = io.contentWindow.document.body?io.contentWindow.document.body.innerHTML:null;
                	xml.responseXML = io.contentWindow.document.XMLDocument?io.contentWindow.document.XMLDocument:io.contentWindow.document;
				} else if (io.contentDocument) {
					xml.responseText = io.contentDocument.document.body?io.contentDocument.document.body.innerHTML:null;
                    xml.responseXML = io.contentDocument.document.XMLDocument?io.contentDocument.document.XMLDocument:io.contentDocument.document;
				}		
            } catch (e) {
				jQuery.handleError(s, xml, null, e);
			}
            if (xml || isTimeout == "timeout") {
                requestDone = true;
                var status;
                try {
                    status = isTimeout != "timeout" ? "success" : "error";
                    // Make sure that the request was successful or notmodified
                    if (status != "error") {
                        // process the data (runs the xml through httpData regardless of callback)
                        var data = jQuery.uploadHttpData(xml, s.dataType);
                        // If a local callback was specified, fire it and pass it the data
                        if (s.success)
                            s.success(data, status);

                        // Fire the global callback
                        if (s.global)
                            jQuery.event.trigger("ajaxSuccess", [xml, s]);
                    } else
                        jQuery.handleError(s, xml, status);
                } catch (e) {
                    status = "error";
                    jQuery.handleError(s, xml, status, e);
                }

                // The request was completed
                if (s.global)
                    jQuery.event.trigger("ajaxComplete", [xml, s]);

                // Handle the global AJAX counter
                if (s.global && ! --jQuery.active)
                    jQuery.event.trigger("ajaxStop");

                // Process result
                if (s.complete)
                    s.complete(xml, status);

                jQuery(io).unbind();

                setTimeout(function() {
                	try {
						jQuery(io).remove();
						jQuery(form).remove();
					} catch(e) {
						jQuery.handleError(s, xml, null, e);
					}
				}, 100);

                xml = null;
            }
        };
        // Timeout checker
        if (s.timeout > 0) {
            setTimeout(function() {
                // Check to see if the request is still happening
                if(!requestDone) uploadCallback("timeout");
            }, s.timeout);
        }
        try {
			var form = jQuery('#' + formId);
			jQuery(form).attr('action', s.url);
			jQuery(form).attr('method', 'POST');
			jQuery(form).attr('target', frameId);
            if (form.encoding) {
				jQuery(form).attr('encoding', 'multipart/form-data');
            } else {
				jQuery(form).attr('enctype', 'multipart/form-data');
            }
            jQuery(form).submit();
        } catch (e) {
            jQuery.handleError(s, xml, null, e);
        }
		
		jQuery('#' + frameId).load(uploadCallback);
        return {abort: function () {}};

    },

    uploadHttpData: function(r, type) {
        var data = !type;
        data = type == "xml" || data ? r.responseXML : r.responseText;
        // If the type is "script", eval it in global context
        if (type == "script")
            jQuery.globalEval(data);
        // Get the JavaScript object, if JSON is used.
        if (type == "json")
			if (data.toLocaleLowerCase().indexOf('<pre>') != -1) {
		    	data = data.substring(5, data.length - 6);
		    }
            eval("data = " + data);
        // evaluate scripts within html
        if (type == "html")
            jQuery("<div>").html(data).evalScripts();

        return data;
    },
    
    handleError: function(s, xhr, status, e) {
		// If a local callback was specified, fire it
		if (s.error) {
			s.error.call(s.context || s, xhr, status, e);
		}

		// Fire the global callback
		if (s.global) {
			(s.context ? jQuery(s.context) : jQuery.event).trigger("ajaxError", [xhr, s, e]);
		}
	}
});